1. PENGANTAR TEKNOLOGI INFORMASI (A)
STORAGE
PENGANTAR TEKNOLOGI INFORMASI (A)
STMIK JAKARTA STI&K
2012

2. Hard Disks What is a disk cache? processor
Portion of memory that processor uses to store frequently accessed items
disk cache
hard disk
first request for data—to disk cache
second request for data—to hard disk

3. Hard Disks What are external hard disks and removable hard disks?
Used to back up or transfer files
Removable hard disk—hard disk that you insert and remove from hard disk drive
External hard disk—freestanding hard disk that connects to system unit

4. Chip and circuits that control transfer of items from disk
Hard Disks
What is a disk controller?
Chip and circuits that control transfer of items from disk
EIDE (Enhanced Integrated Drive Electronics) controller supports four hard disks, provides connections for CD and DVD drives
SCSI (Small Computer System Interface) controller supports up to fifteen devices including hard disks, CD and DVD drives, tape drives, printers, scanners, network cards

5. Hard Disks What is an Internet hard drive?
Service on Web that provides storage for minimal monthly fee
Files can be accessed from any computer with Web access
Large files can be downloaded instantaneously
Others can be authorized to access your data

6. CDs and DVDs What are CDs and DVDs?
Push the button to slide out the tray.
Flat, round, portable metal discs made of metal, plastic, and lacquer
Can be read only or read/write
Insert the disc, label side up.
Most PCs include CD or DVD drive, most play audio CDs
Push the same button to close the tray.

7. CDs and DVDs How does a laser read data on a CD or DVD? laser diode
prism
light- sensing diode 1
lens
pit
land
disc label
Step 3. Reflected light is deflected to a light-sensing diode, which sends digital signals of 1 to computer. Absence of reflected light is read as digital signal of 0.
Step 2. If light strikes a pit, it scatters. If light strikes a land, it is reflected back toward diode.
Step 1. Laser diode shines a light beam toward disc.

8. CDs and DVDs How is data stored on a CD or DVD?
Typically stored in single track
Track divided into evenly sized sectors that store items
single track spirals to edge of disc
disc sectors

9. CDs and DVDs How should you care for a CD or DVD?
Do not expose the disc to excessive heat or sunlight
How should you care for a CD or DVD?
Do store the disc in a jewel box when not in use
Do not eat, smoke, or drink near a disc
Do not stack discs
Do hold a disc by its edges
Do not touch the underside of the disc

10. CDs and DVDs What is a CD-ROM? Compact disc read-only memory
Cannot erase or modify contents
Typically holds MB to 1 GB
Commonly used to distribute multimedia and complex software

11. Ranges from 48X to 75X or faster 75X is 150 KBps (KB per second)
CDs and DVDs
What is the data transfer rate of a CD-ROM drive?
Ranges from 48X to 75X or faster
75X
75  150 KBps = 11,250 KBps or MBps
75X is 150 KBps (KB per second)
48X: 48  150 KBps = 7,200 KBps or 7.2 MBps

12. CDs and DVDs What is a Picture CD?
Film developers offer Picture CD service
Can be modified using photo editing software
Stores digital versions of roll of film
Step 1. Drop off film to be developed. Mark the Picture CD box on the film-processing envelope.
Step 3. At home, print images from Picture CD on your ink-jet photo printer.
Step 2. When you pick up prints and negatives, a Picture CD contains digital images of each photograph.
At a store, print images to Picture CD at kiosk.

13. CDs and DVDs What are CD-Rs and CD-RWs?
Must have CD recorder or CD-R drive
CD-R (compact disc-readable)
—cdisc you can write on once
Cannot erase disc’s contents
CD-RW (compact disc-rewritable)
—ceerasable disc you can write on multiple times
Must have CD-RW software and CD-RW drive

14. CDs and DVDs How is an audio CD created? From a purchased CD. . .
Step 1. Artist composes a song.
Step 2. Song is stored on audio CD and purchased by user.
Step 3. User inserts audio CD into CD drive, plays song, and rips desired tracks onto hard disk.
Step 5. User listens to song on a personal computer or removes CD and listens to song on a portable CD player.
Step 4. User copies file to a CD-RW disc.

15. CDs and DVDs How is an audio CD created? From the Internet. . .
Step 2. Song is compressed and stored on the Internet.
Step 1. Artist composes a song.
Step 3. User pays for and downloads song as audio file onto a hard disk.
Step 5. User listens to song on a personal computer or removes CD and listens to song on a portable CD player.
Step 4. User copies file to a CD-RW disc.

16. CDs and DVDs
What is a DVD-ROM (digital versatile disc-ROM or digital video disc-ROM)?
High capacity disc capable of storing 4.7 GB to 17 GB
Must have DVD-ROM drive or DVD player to read DVD-ROM
Stores databases, music, complex software, and movies
DVD
DVD drive

17. DVD-ROM Storage Capacities
CDs and DVDs
How does a DVD-ROM store data?
Two layers of pits are used, lower layer is semitransparent so laser can read through
Some are double-sided
DVD+RW is a rewritable DVD
DVD-ROM Storage Capacities
Sides Layers Storage Capacity GB GB GB GB